Who's affected?

In the UK, pneumonia affects around 8 in 1,000 adults each year. It's more widespread in autumn and winter.

Pneumonia can affect people of any age, but it's more common – and can be more serious – in certain groups of people, such as the very young or the elderly.

People in these groups are more likely to need hospital treatment if they develop pneumonia.

What causes pneumonia?

Pneumonia is usually the result of a pneumococcal infection, caused by bacteria called Streptococcus pneumoniae.

Many different types of bacteria, including Haemophilus influenzae and Staphylococcus aureus, can also cause pneumonia, as well as viruses and, more rarely, fungi.

As well as bacterial pneumonia, other types include:

viral pneumonia – most commonly caused by the respiratory syncytial virus (RSV) and sometimes influenza type A or B; viruses are a common cause of pneumonia in young children

aspiration pneumonia – caused by breathing in vomit, a foreign object, such as a peanut, or a harmful substance, such as smoke or a chemical

fungal pneumonia – rare in the UK and more likely to affect people with a weakened immune system

hospital-acquired pneumonia – pneumonia that develops in hospital while being treated for another condition or having an operation; people in intensive care on breathing machines are particularly at risk of developing ventilator-associated pneumonia

Risk groups

The following groups have an increased risk of developing pneumonia:

babies and very young children

elderly people

people who smoke

people with other health conditions, such as asthma, cystic fibrosis, or a heart, kidney or liver condition

people with a weakened immune system – for example, as a result of a recent illness, such as flu, having HIV or AIDS, having chemotherapy, or taking medication following an organ transplant

Diagnosing pneumonia

Your GP may be able to diagnose pneumonia by asking about your symptoms and examining your chest. Further tests may be needed in some cases.

Pneumonia can be difficult to diagnose because it shares many symptoms with other conditions, such as the common cold, bronchitis and asthma.

To help make a diagnosis, your GP may ask you:

whether you feel breathless or you're breathing faster than usual

how long you've had your cough, and whether you're coughing up mucus and what colour it is

if the pain in your chest is worse when you breathe in or out

Your GP may also take your temperature and listen to your chest and back with a stethoscope to check for any crackling or rattling sounds.

They may also listen to your chest by tapping it. Lungs filled with fluid produce a different sound from normal healthy lungs.

If you have mild pneumonia, you probably won't need to have a chest X-ray or any other tests.

You may need a chest X-ray or other tests, such as a sputum (mucus) test or blood tests, if your symptoms haven't improved within 48 hours of starting treatment.

Treating pneumonia

If you don't have any other health problems, you should respond well to treatment and soon recover, although your cough may last for some time.

It’s usually safe for someone with pneumonia to be around others, including family members.

However, people with a weakened immune system are less able to fight off infections, so it's best they avoid close contact with a person with pneumonia.

For at-risk groups, pneumonia can be severe and may need to be treated in hospital. This is because it can lead to serious complications, which in some cases can be fatal, depending on a person's health and age.